这是我第一次尝试编写自己的静态合并方法。随意戳孔。
import com.google.gson.JsonArray;import com.google.gson.JsonElement;import com.google.gson.JsonObject;import java.util.Map;public class GsonTools { public static enum ConflictStrategy { THROW_EXCEPTION, PREFER_FIRST_OBJ, PREFER_SECOND_OBJ, PREFER_NON_NULL; } public static class JsonObjectExtensionConflictException extends Exception { public JsonObjectExtensionConflictException(String message) { super(message); } } public static void extendJsonObject(JsonObject destinationObject, ConflictStrategy conflictResolutionStrategy, JsonObject ... objs) throws JsonObjectExtensionConflictException { for (JsonObject obj : objs) { extendJsonObject(destinationObject, obj, conflictResolutionStrategy); } } private static void extendJsonObject(JsonObject leftObj, JsonObject rightObj, ConflictStrategy conflictStrategy) throws JsonObjectExtensionConflictException { for (Map.Entry<String, JsonElement> rightEntry : rightObj.entrySet()) { String rightKey = rightEntry.getKey(); JsonElement rightVal = rightEntry.getValue(); if (leftObj.has(rightKey)) { //conflict JsonElement leftVal = leftObj.get(rightKey); if (leftVal.isJsonArray() && rightVal.isJsonArray()) { JsonArray leftArr = leftVal.getAsJsonArray(); JsonArray rightArr = rightVal.getAsJsonArray(); //concat the arrays -- there cannot be a conflict in an array, it's just a collection of stuff for (int i = 0; i < rightArr.size(); i++) { leftArr.add(rightArr.get(i)); } } else if (leftVal.isJsonObject() && rightVal.isJsonObject()) { //recursive merging extendJsonObject(leftVal.getAsJsonObject(), rightVal.getAsJsonObject(), conflictStrategy); } else {//not both arrays or objects, normal merge with conflict resolution handleMergeConflict(rightKey, leftObj, leftVal, rightVal, conflictStrategy); } } else {//no conflict, add to the object leftObj.add(rightKey, rightVal); } } } private static void handleMergeConflict(String key, JsonObject leftObj, JsonElement leftVal, JsonElement rightVal, ConflictStrategy conflictStrategy) throws JsonObjectExtensionConflictException { { switch (conflictStrategy) { case PREFER_FIRST_OBJ: break;//do nothing, the right val gets thrown out case PREFER_SECOND_OBJ: leftObj.add(key, rightVal);//right side auto-wins, replace left val with its val break; case PREFER_NON_NULL: //check if right side is not null, and left side is null, in which case we use the right val if (leftVal.isJsonNull() && !rightVal.isJsonNull()) { leftObj.add(key, rightVal); }//else do nothing since either the left value is non-null or the right value is null break; case THROW_EXCEPTION: throw new JsonObjectExtensionConflictException("Key " + key + " exists in both objects and the conflict resolution strategy is " + conflictStrategy); default: throw new UnsupportedOperationException("The conflict strategy " + conflictStrategy + " is unknown and cannot be processed"); } } }}
